Carboxylation



Dem-2,1969 E. J.,M'ILLE R, JR., ET 3,431,977

CARBOXYLATION Original Filed April 26, 1965 EFFECT OF INCREASING AMOUNTOF HF ACID F ORMED I 1 l l I l I I /0 I5 MOLE 6 HF per MOLE UNSATURATEDAC/ D INVENTORS Eugene J M/Y/er, Jr Ago Mo/s BY Domingo Soy UnitedStates Patent 3,481,977 CARBOXYLATION Eugene J. Miller, Jr., Wheaton,Ago Mais, La Grange Park, and Domingo Say, Chicago, Ill., assignors toArmour and Company, Chicago, Ill., a corporation of DelawareContinuation of application Ser. No. 450,993, Apr. 26, 1965. Thisapplication July 10, 1968, Ser. No. 752,432 Int. Cl. C07c 57/04, 57/16,57/12 U.S. Cl. 260537 6 Claims ABSTRACT OF THE DISCLOSURE Unsaturatedfatty acids are carboxylated with carbon monoxide by the use of 15 to 30moles of HF per mole of acid.

This application is a continuation of application Ser. No. 450,993 filedApr. 26, 1965, now abandoned.

This invention relates to carboxylation, and more particularly, to thecarboxylation of unsaturated fatty acids with carbon monoxide in thepresence of hydrogen fluoride to effect extremely high yields of highquality diacids.

Roe and Swern of the U.S. Department of Agriculture in the Journal ofthe American Oil Chemists Society periodical, volume 37, pages 661 to668 (1960), report that unsaturated fatty acids may be carboxylated withcarbon monoxide using large amounts of H SO Isolation of the product wasaccomplished, however, by dousing the reaction mixture in water.Economical reclamation of the sulfuric acid catalyst from this aqueousmixture presents difliculties which leave the process far from being acommercial one. This is unfortunate because the product, carboxy-fattyacid, is extremely attractive in various technologies. It not onlypossesses the desirable physical and chemical properties of a long chainfatty acid, but, in addition, has a second carboxy group which makes itextremely useful as an intermediate for forming bifunctional fattycompounds and as a monomeric material in polyester work. Other uses willbecome evident as this disclosure proceeds.

It should be evident that if one could accomplish substantiallyquantitative yields with practically quantitative reclamation ofcatalyst, an extremely valuable advance would be made.

An object of this invention is to provide an improved carboxylationprocess for unsaturated fatty acids.

Another object is to provide a carboxylation process of the abovecharacter, which utilizes relatively mild reaction conditions.

Still another object is to provide a carboxylation process of the abovecharacter which is relatively fast.

A further object is to provide a carboxylation process for unsaturatedfatty acids having high yield, in fact, almost quantitative.

A still further object is to provide a carboxylation process of theabove character which allows for almost quantitative recovery of thecatalyst in usable form.

Other objects of the invention will in part be obvious and will in partappear hereinafter:

It has now been sur isingly found that substantially quantitative yieldsof dicarboxylic acids may be obtained by the carboxylation ofunsaturated fatty acids if 'one utilizes liquid hydrogen fluoride as acatalyst, in the nature of solvent quantities. The molar ratio ofunsaturated acid to HF should range from about 1:15 to 1:30 or more,although no improvement in yield is effected by the use of greater than30 moles of HF per mole of unsaturated acid.

A molar equivalent or slightly in excess of a molar equivalent of water(based on the unsaturated acid) is Patented Dec. 2, 1969 also used withsaid large amounts of HF. The use of less than equivalent amounts ofwater would tend to favor formation of by-products, such as ester, whilelarge excesses of water would only serve to dilute the HF unnecessarily,thereby complicating efiicient catalyst recovery.

Carbon monoxide, which serves as the carboxylating agent, should be usedat pressures ranging from slightly superatmospheric to 1000 p.s.i.g.,the prime essential be ing intimate contact between the gaseous andliquid reaction phases. A preferred range of carbon monoxide pressure is50 to 500 p.s.i.g.

When such ratios are utilized, over dicarboxylic acid is generallyformed. As indicated hereinafter, the sharp breakoff in percent diacidformed depends upon utilization of the concentration ranges and ratiosindicated above.

Isolation of the carboxy-fatty acid formed under said concentrationranges and ratios is accomplished by distillation of the HP from thereaction mixture with subsequent recovery. Almost quantitative recovery,generally in the range of 97-99%, of the HF can be eifected in this way.The concentration of recovered HP is usually within the range of -98%,which is suitable for reuse in carboxylation reactions.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following examples which illustrate theinvention in detail:

EXAMPLE I A l-liter Monel autoclave is charged with 415 g. (20.75 moles)of liquid hydrogen fluoride and 19.8 g. (1.1 moles) of water. The unitis sealed and the temperautre raised to 30 C. Carbon monoxide gas isintroduced to a pressure of 50 p.s.i.g. and 278 g. (1.0 mole) ofcommercial oleic acid are pumped in over a one hour period at 30 C/50p.s.i.g. The reaction is allowed to proceed under these conditions foran additional hour. Then at the end of one hour, the stirring is stoppedand the hydrogen fluoride distilled off under a 5 p.s.i.g. nitrogenpurge at temperatures ranging from 30 C. to a maximum of 150 C.

Total HF recovery (99%) g 410 Total HF concentration percent 95 Crudecarboxystearic (302 g.) is obtained in 92% mass yield having thefollowing analysis: Neutralization equivalentl98 (calculated 173.2).

TABLE OF PHYSICAL AND CHEMICAL PROPERTIES [Solubility Data (Weight toWeight Basis) at 25 0.] Solvent:

Isopropanol. 10%

Benzene, 10%

Iso-octane, 10%

Kerosene, 10%

Skelly F, 10%

Mineral Oil, 10%

Water, Insoluble EXAMPLE II The oleic acid used in this carboxylation iscommercial grade consisting of about 93% active, the remainder beingsaturated acids. The mole ratio of oleic acid: HF:H O is 10:20: 1.3.

A 300-ml. Monel autoclave is charged with g. (6.0 moles) of liquidhydrogen fluoride and 7.02 g. (0.39 mole) of water at approximately 0 C.The unit is secured and temperature is taken up to 25 C. Carbon monoxidegas is introduced to a pressure of 500 p.s.i.g. and then 84.15 g. (0.3mole) of oleic acid is pumped into the reaction mixture over a period ofone hour at 25-29 C./ 320-500 p.s.i.g. The reaction is allowed toproceed for an additional 30 minutes at 25-27 C./300500 p.s.i.g. Thenthe reactive mixture is cooled to about C., and the unit vented andopened. The reaction mixture is transferred to a 500 ml. round-bottomstainless steel flask (equipped with a magnetic stirrer, thermocoupleand heating mantle). Hydrogen fluoride is distilled off by heating andstirring over a period of 3 hours at 16160 C. Carboxystearic acid willbe obtained as a dark oil in 97.0% mass yield (95.7 g.) having thefollowing analysis:

Neutralization equivalent (calculated 173.2) 186.5 Activity (percent)92.8 Saponification equivalent 183.5 Iodine value 6.81

EXAMPLE III Netralization equivalent (calculate 115.1) 153.5 Activity(percent) 75.0 Saponification equivalent 134.4 Iodine value 10.6

EXAMPLE IV In like manner, erucic acid is carboxylated using a moleratio of acid: HF:H O of 1.0:20.0:1.2 at 25-30 C./300450 p.s.i.g. carbonmonoxide pressure. The HF is removed by distillation, as in Example II,yielding carboxybenhenic acid in essentially quantitative yield havingthe following analysis:

Neutralization equivalent (calculated 192.3) 215 Activity (percent) 89.5Saponification equivalent 206.5 Iodine value 3.6

EXAMPLE V TO X In order to ascertain the effect of varying theconcentration of unsaturated acid (specifically oleic acid), HF andwater, a series of runs are made using essentially the same method asillustrated in Example II. The results are tabulated as follows:

'4 in accordance with the method of this invention are those fallingwithin the following formula:

x+y+z=5 to 19 a+b=1 to 3, and either may be 0.

Typical of such fatty acids are 10-undecenoic acid, lauroleic acid,myristoleic acid, palmitoleic acid, oleic acid, gadoleic acid, erucicacid, linoleic acid, linolenic acid, eleostearic acid, licanic acid,arachidonic acid and clupanodonic acid. Most of these are found innatural fats and oils such as vegetable, animal and marine fats andoils. If desired, mixtures of unsaturated fatty acids may becarboxylated by the technique of this invention.

It will thus be seen that the objects set forth above, among those madeapparent from the preceding description, are efficiently attained, andsince certain changes may be made in carrying out the above methodwithout departing from the scope of the invention, it is intended thatall matter contained in the above description shall be interpreted asillustrative and not in a limiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention, which, as amatter of language, might be said to fall therebetween.

Now that the invention has been described, what is claimed as new anddesired to be secured by Letters Patent is:

What is claimed is:

1. A method for the carboxylation of unsaturated fatty acids fallingwithin the formula:

x+y+z=5 to 19 a+ b=1 to 3, and either may be 0.

to form dicarboxylic acids comprising adding in a one step process atleast one unsaturated fatty acid to an autoclave containing carbonmonoxide at pressures ranging from slightly superatmospheric to 1000p.s.i.g. and a mixture of about 15 to 30 moles of hydrogen fluoride permole of said unsaturated fatty acid and water slightly in excess of astoichiometric quantity of said unsaturated fatty acid.

1 The neutralization equivalent of pure earboxystearic acid is 164.2.Allowing for the 7% saturated acids present in commercial grade oleicacid, however, raises the neutralization equivalent theoreticallyobtainable to 173.2.

2 Mass yield was not calculated in this case since no diacid was formedas evidenced by the high neutralization equivalent.

From this table and the graph attached it is evident that the use of atleast 15 moles of HP to one mole of unsaturated acid is critical inorder to obtain satisfactory conversions to the carboxy-fatty acid. Aquantity of HF sufiicient to dissolve the unsaturated acid appears to bethe prime requirement. The practical upper limit of moles of HF per moleof unsaturated acid is about 30, although higher quantities may beutilized if desired.

to form dicarboxylic acids comprising the steps of adding Theunsaturated fatty acids that may be carboxylated in a one step processat least one unsaturated fatty acid to an autoclave containing carbonmonoxide at pressures ranging from slightly superatmospheric to 1000p.s.i.g. and a mixture of about 15 moles to 30 moles to each mole ofsaid unsaturated fatty acid of hydrogen fluoride as a catalyst-solventand water slightly in excess of a stoichiometric quantity to saidunsaturated fatty acid and subsequently distilling off the hydrogenfluoride to eflfect a high yield of a high quality dicarboxylic acid aswell as good recovery of the hydrogen fluoride.

3. The method of claim 2 wherein the unsaturated fatty acid used isoleic acid.

4. The method of l-claim 2 wherein the unsaturated fatty acid used isl0-undecenoic acid.

5. The method of claim 2 wherein the unsaturated fatty acid used iserucic acid.

6. The method of claim 2 wherein the unsaturated fatty acids usedconsist of a mixture of fatty acids as found in natural fats and oils.

References Cited JAMES A. PATTEN, Primary Examiner V. GARNER, AssistantExaminer

